Starting Tubers Indoors

• If you want to get an early start on your garden, start begonia tubers indoors in late winter or early spring, about eight weeks before the likelihood of frost passes for your area. You'll need to plant the tubers either in small seed-starting pots or in flats designed for starting plants indoors, White Flower Farms says. Plant them in potting mix with the hollow side facing up. Cover each tuber with a 1/2 inch of soil, then water lightly to keep the soil moist but not waterlogged. Keep the plants in a warm, sunny spot until they are ready to move outdoors.
  
  

Transplanting Young Plants

• Wait until the danger of frost has passed before planting young begonias -- either those you started indoors yourself or plants you purchased from a nursery or garden center. It's a good idea to start the plants indoors or directly plant young begonias because it typically takes more than three months for the plants to reach the blooming stage, the Iowa State University Extension reports. However, if you are looking for an option for late-season color, begonias can serve this need.
  
  

Site Requirements

• Begonias need some light, but they do best with morning sun and afternoon shade, the University of Minnesota Extension reports. They also require some protection from high winds. Finally, as with most other garden plants, begonias prefer a well-draining soil. If your soil quality is suspect, incorporate some organic matter into the dirt at planting time to improve drainage.
  
  

Care and Maintenance

• Once planted, begonias will benefit from regular attention. Check moisture levels and apply fertilizer as needed. Water the plants only when the soil is dry to the touch because waterlogged soil can cause the plant stems to break, White Flower Farms reports. A water-soluble fertilizer will help improve the quality and appearance of the flowers. Use a 20-20-20 fertilizer monthly during the growing season. Deadheading spent flowers can also improve the appearance of the plant and help extend the blossoming period.